The present invention relates generally to optical panels, and more specifically to thin optical display panels comprising optical waveguides.
Optical display screens are found in many common applications such as televisions, computer displays, and displays for industrial and scientific equipment. Common display screens form images using a cathode ray tube (CRT) which is relatively long and requires a large enclosure.
Rear projection television (RPTV) displays utilize image light which is projected to the back side of a screen for displaying the image on its front side. The resulting enclosures for these RPTV displays have a considerable depth for accommodating the necessary optical components for focusing, enlarging, and directing the image light.
Thin display screens of various forms are continually being developed for replacing CRTs to minimize the screen enclosure and overall weight. A common thin panel uses a liquid crystal display (LCD) for modulating light therethrough for creating video images.
Another type of thin display panel includes thin optical waveguides laminated together in a thin wedge shape through which image light is internally reflected between a narrow inlet face and a large outlet screen. U.S. Pat. No. 5,381,502 is one of a series of patents based on this technology being developed for improving performance of thin display panels.
Yet another type of thin optical display being developed includes a prismatic optical film for turning incident light up to about 90°. The film requires a light incidence angle between 0° and 20°, and a corresponding depth between the film and the image light source in which to spread the light across the entire surface of the film. As the size of the display increases, the required depth behind the display increases, thusly increasing the overall thickness or depth of the enclosure.
Accordingly, it is desired to further reduce the overall thickness or depth of the enclosures for optical displays.